The Left has traditionally assumed that human nature is so malleable, so perfectible, that it can be shaped in almost any direction. By contrast, a Darwinian science of human nature supports traditionalist conservatives and classical liberals in their realist view of human imperfectibility, and in their commitment to ordered liberty as rooted in natural desires, cultural traditions, and prudential judgments. Arnhart's email address is larnhart1@niu.edu.

Monday, June 09, 2008

Daniel Smail and the Neuroscience of History

At the end of August, I will be presenting a paper in Boston at the annual meetings of the American Political Science Association on "Biopolitical Science: Darwin, Lincoln, and the Deep History of Politics." This paper will be part of a series of panels on "Evolution and Morality" sponsored by the American Society for Political and Legal Philosophy. For my paper, there will be written responses from Daniel Lord Smail, a historian at Harvard, and Richard Richards, a philosopher at the University of Alabama.

The very idea of "deep history" is one that I have borrowed from Smail, particularly as he develops it in his recent book On Deep History and the Brain (University of California Press, 2008). Smail points out that historians today assume that the true "history" of humanity began about 5,000 years ago with the invention of writing, and so everything else that happened to human beings prior to that is dismissed as "prehistory." Noting that there is plenty of evidence for human life prior to writing, Smail suggests there is no good reason why historians shouldn't develop a grand historical narrative that would encompass the whole of human experience from the Paleolithic era to the present.

That few historians today can even conceive of this reflects what Smail calls "the grip of sacred history." In the Western world, the influence of biblical religion led historians for many centuries to assume that history began about 6,000 years ago with the divine creation of Adam and Eve. Even when secular historians in the eighteenth and nineteenth centuries began to break away from the biblical creation story, they still held onto a secular version of this story: they assumed that history began about 6,000 years ago with the invention of agriculture and writing in Mesopotamia. Whatever happened to human beings prior to this was set aside as "prehistory."

In his new book, Smail argues for rejecting the chronological limits of sacred history and pursuing the study of deep history as including the entire genetic and cultural history of humanity. This would require interdisciplinary research combining traditional history and biological science. He offers an outline of how this could be done by concentrating on neurohistory--the history of humanity based on the evolution of the human brain. For this, historians would apply contemporary neuroscience to the study of human history. Historians must always employ psychological assumptions about human motivations in their historical explanations. Smail suggests that neuroscience would provide historians a psychological science rooted in modern biology.

One example of neurohistory for Smail is explaining the human dominance hierarchies that arose after the agricultural revolution allowed small groups of elite individuals to rule over large groups of subordinates. Dominant individuals must employ whatever devices they can to induce submissive dispositions in their subordinates. In matriarchal baboon societies, high-ranking females harass subordinate females in ways that create high levels of stress. Similarly, we might expect that in human dominance hierarchies, high-ranking individuals would intimidate their subordinates in ways that would generate stress hormones that make them feel submissive.

At one level, such an explanation might seem so obvious as to be trivial. After all, if subordinate individuals are submissive towards dominant individuals, one would assume that there must be some kind of biochemical state in the brains of the subordinates associated with a psychic state of submission. But at another level, such a explanation might seem dubious insofar as they are untestable. Because there is no way to gather neurophysiological data from the distant past to support the explanations. Smail admits this, but argues that even without direct tests of his neurophysiological hypotheses, we might find support in the historical sources for such neurohistorical reasoning. Knowledge of human neurophysiology offers an interpretive framework within which we might generate historical explanations that are heuristically powerful.

More generally, Smail argues for viewing cultural history as depending on "psychotropic mechanisms"--behavioral practices and institutional structures that have neurochemical effects that shape human moods. We might view each kind of social order as having a distinct psychotropic profile. For example, we might explain the medieval church as shaping the behavior of believers through ceremonial rituals and religious practices that modulate the chemical messengers in the brain in ways that sustain dependence on the church. But then in the eighteenth century, there was a clear decline in religious activities, which might be correlated with the popularity of new psychotropic commodities like coffee, tobacco, and alcoholic drinks like gin and rum. In fact, much of the public life of European cities in the eighteenth century was centered in coffeehouses and cafes.

To be persuaded of Smail's specific explanations, I would need more evidence and argumentation than he provides in his book. But I can accept his general idea--that every form of social order must appeal to the human nervous system by shaping the neurochemical activity of individuals to support the behavioral patterns of that society. I have argued that there are at least twenty natural desires that are universal to all human societies because they are rooted in human biological nature, and these twenty natural desires provide a universal basis for moral and political experience. These natural desires constrain but do not rigidly determine the customary traditions of social life. And within the constraints of natural desires and customary traditions, there is still some freedom for the exercise of prudential judgment by individuals. I would say that what Smail calls "psychotropic mechanisms" are the various means by which a social order modulates the neurochemistry corresponding to the twenty natural desires.

Although Smail's neurohistory has much in common with evolutionary psychology, he criticizes the evolutionary psychologists in the tradition of Cosmides and Tooby for being too ahistorical in their reasoning, because they jump from the "environment of evolutionary adaptation" as shaped in the Paleolithic era to the modern present without any account of the historical development from one to the other. Although Smail agrees with the evolutionary psychologists that the genetic evolution of the human species has shaped the human brain to manifest the predispositions of human nature, he thinks the evolutionary psychologists don't go far enough in recognizing the plasticity of that brain and how that neural plasticity makes possible cultural history. Like David Sloan Wilson, Smail emphasizes the need for explaining human behavior as shaped by gene-culture coevolution, and for that we need neurohistory.

I would say that what we need here is a theoretical framework of constrained plasticity that moves through three levels of social order--the natural history of the human species, the cultural history of human groups, and the individual history of the human beings in each group.

Smail has been influenced by David Buller's critique of evolutionary psychology in his book Adapting Minds. Stressing the diversity and contingency of human behavior and thought over evolutionary time, Buller concludes that "human nature is a superstition" (480). But I would say this is just as mistaken as concluding that since no two human beings have exactly the same anatomical structures, human anatomy is a superstition. While recognizing the anatomical diversity and contingency of human beings, the science of human anatomy presumes only that there is sufficient regularity in the patterns of human anatomical structure to warrant the generalizations of anatomy. Similarly, the science of human behavioral nature presumes that there is enough regularity in the patterns of human behavioral nature to warrant the study of human nature. In fact, Smail speaks about the need for broad categories of patterns or tendencies in studying human nature to support any deep history of human life. My account of the twenty natural desires specifies such patterns as manifesting a human nature grounded in the regularity of human neurophysiology.

1 comment:

Anonymous
said...

Interesting post, but I'm not sure I buy the comparison between Buller's rejection of human nature and the rejection of human anatomy. Human nature can only be measured in terms of behavior, feelings, and thoughts, none of which are meaningful indicators except when understood in the context of culture and environment. To say, as people often do, "it's human nature to be greedy" presupposes some idea of greed which itself is culturally determined.